Method for continuous pressing



1967 N. R. ALENIUS METHOD FOR CONTINUOUS PRESSING 5 Sheets-Sheet 1Original Filed Oct.

Md I

INVENTOR.

Nils Robert Alenius ATTORNEYS Dec. 5, 1967 R. ALENIUS 3,356,014

METHOD FOR CONTINUOUS PRESSING Original Filed Oct. 1, 1962 5Sheets-Sheet 2 FIGS BY Nils Roberr Alenius ATTORNEYS Dec. 5, 1967 Us3,356,014

METHOD FOR CONTINUOUS PRESSING Original Filed Oct. 1, 1962 3Sheets-Sheet 5 FIG. 9

v INVENTOR.

Nils Robert Alenius ATTORNEYS UnitedStates Patent 2 Claims. (Cl. 100-35)ABSTRACT OF THE DISCLOSURE Method for continuous pressing especiallyapplicable to the pressing of materials produced in the form of acontinuously progressing, unbroken mat.

This application is a division of my application Ser. No. 227,470, filedOct. 1, 1962, entitled, Apparatus for Continuous Pressing, and nowUnited States Letters Patent No. 3,202,090, issued on Aug. 24, 1965.

This invention relates to a method for continuous pressing which isespecially applicable to the pressing of materials produced in'the formof a continuously progressing, unbroken mat. Materials for which thiskind of pressing is suitable include different types of wooden andfibrous boards, plywood, laminated panels, composite boards, etc. Thepressing operation, as contemplated by the invention, is carried outduring the continuous travel of the mat of material, and is effected bya mobile press in such a way that after the completion of the pressingoperation the-material still comprises an unbroken, continuous mat fromwhich may be cut the panels desired. It is obvious that this type ofpressing offers many advantages over the traditional method of batchpressing, a fact commonly recognized by the trade. By continuouspressing, very considerable savings are made both as re gards materialand labour and other production costs; in addition, one valuableadvantage gained is that the final panels, contrary to what is possiblein traditional practice, can be had in any length irrespective of thelength of the press used.

It is known that the art of continuous pressing may be employed by theuse of stationary presses in which the pressure is eifected by means ofpress plates which consist of either a pair of travelling, endlesspressing belts, or oscillating superimposed pressing plates or rails.However the practical value of these presses is almost entirelydestroyed by the technical disadvantage that the total pressing power ofthe mobile pressing elements must be derived from the stationary pressframe. The transference of the immense power required for the pressingcan be accomplished only by the intermediation of friction reducingrolls, bearings or similar means, but this expedient makes theconstruction of the presses very intricate and expensive, and seriouslycomplicates their operation and maintenance. The disadvantages of thisconstructional drawback are in fact so considerable that this type ofpress has found no practical use in the industry concerned with themanufacture of boards and panels.

It is an object of this invention to provide a method by which theadvantages of continuous pressing can be achieved in a simpler, morepractical, and less expensive way than that described above. Theprincipal feature of this method is that the progressing material mat tobe pressed is conveyed through a .press between its press plates; thispress is mobile, and is moved forwards and backwards in the direction ofmovement of the material mat in such a way that the forward movement ofthe press, which corresponds in direction to that of the material mat,and during which movement the section of the material mat within thepress is being pressed, is

synchronous with the progress of the material during the act ofpressing. Subsequent to completion of the pressing, the backwardmovement of the press returns it to the starting point of its forwardmovement, thus enabling the operation cycle to be repeated on the nextsection of the mat of material to be pressed.

Another object of the present invention is the provision of an apparatusfor the implementation of the pressing method indicated above. In itsgeneral embodiment, the apparatus comprises a one-opening sheet press,mobile on a track, between the press plates of which is conveyed theprogressing material mat, and which press is moved forwards andbackwards in the travel direction of the material mat in such a way thatthe forward movement of the press, which corresponds to that of thematerial mat, and during which movement the section of the material matwithin the press is being pressed, synchronizes the progress of thematerial mat during the act of pressing; the backward movement of thepress after the completion of the pressing returns the press to thestarting point of its forward movement, in order to enable the operationcycle to be repeated on the next section of the mat of material to bepressed.

A further object of the invention is that of providing a simple andreliable means of attaining absolute synchronization between theforward, pressing movement of the press and the travel of the material,as even the slightest deviation with respect to the speed could proveinjurious to the unpressed material in front of the press. According tothe invention this important feature of the process is controlled byhaving the forward movement of the press, is. that of the direction oftravel of the material, caused by a force which continuously andindependently of the rate of travel of the press tries to move the pressat a greater speed than that of the material, but which is checked by ablocking device operating in unison with the progress of the material,and bringing the movement of the press into complete synchronizationwith the travel of the material mat. Consequently, the force whicheffects the forward movement of the press must be of yielding andflexible nature. Means for the provision of this kind of force include apneumatic motor or pressure cylinder, a hydraulic motor or pistonprovided with an overflow valve, an alternating current motor connectedwith a sliding coupling, a direct current motor, or a suspended weightwhich acts on the press or on its drive by means of a wire.

Other objects and advantages will appear in the following description,and the novel features of the method are particularly pointed out in theclaims appended.

This invention is described in the followng with reference to theenclosed drawing, which schematically shows an embodiment of theinvention.

FIG. 1 is a side elevation of the mobile press and its track;

FIG. 2 shows the press in cross section through IIII of FIG. 1;

FIG. 3 is a plan view of an embodiment of the drive and the powertransmission for the forward and backward motion of the press;

FIG. 4 is a partial side elevation of the drive shown in FIG. 3;

FIG. 5 is a side elevation view of another embodiment of the powertransmission shown in FIG. 3;

FIG. 6 is a similar view of another form;

FIG. 7 is a plan view of another embodiment of the drive for the forwardand backward motion of the press;

FIG. 8 illustrates a detail of the control equipment, which enablesmaneuvering of the forward and backward movement of the press; and

FIG. 9 is an end elevation of another embodiment of 3 the mobile presshaving tanks for the provision of heating and cooling agents.

If similar details are shown in different figures, they have the samereference symbols.

The press shown in FIGS. 1 and 2 comprises a frame constructon 1furnished with a pair of superimposed press plates '3 and 4, of whichplate 4 is fixed to the frame construction, whereas plate 3 isvertically movable by the aid of hydraulic jacks 18, in their turncontrolled by pump equipment 19 driven by electromotor 20. Press frame 1is mounted on a number of Wheels 5, which enable the press to be movedforward and backward in press track 6. The continuously travellingmaterial, on a carrier band or alone, indicated by dash lines 2, isconveyed between pressplates 3 and 4, the direction of travel of the mathere being that of the forward stroke of the press. Through a drive,whose construction is described below, the movements of the mobile pressare etfectuated so that at the beginning of the forward stroke, thepress is at the right end of the track according to FIG. 1, it is thenaccelerated to the speed of the travelling material mat, and once it hasreached it, hydraulic jacks 18 are actuated in order to tighten thepress plates against the material mat. The press is then movedsynchronously with the travel of the mat for a distance whichcorresponds to the pressing time, and following this, the press havingreached the end of the forward stroke at the other end of the track, thepressure of the jacks is released and the press plates separated. Thisdone, the press is removed to the starting point of the forward stroke,and the operation cycle repeated. In order to shorten the time of thecycle, the return stroke can be elfectuated at a speed higher than thatof the synchronous forward movement. The length of the press and itstravelling stroke are so dimensioned in relation to each other that eachpressing stroke somewhat overlaps the section pressed at the precedingstroke, resulting in the material mat being pressed without a break overthe whole of its length.

In order to speed up the act of pressure, the press plates are heated,and are to this end furnished with borings 17 through which is passed aheating agent. The agent, if a liquid or gas, is transmitted to thepress plates from a stationary source by means of flexible tubes, togglejoint pipes, or similar devices, which are capable of following thepress in its motion forward and backward. In the embodiment according toFIG. 1 the heat transference is made by means of toggle jointed pipes 8and 9. The stationary ends of the pipe systsem are mounted on a mastconstruction 7 bridging the press track.

Another way of having a fluid heating agent conveyed to the mobile pressis shown in FIG. 9. According to this method, the heating agent isprovided in an open, long tank '51 located along the track of the press.From this tank, irrespective of the movement of the press, the heatedliquid is conveyed to the press by pump 52, and after circulation, islet back into the tank for reheating. Of course, forthis kind of heatconveyance, it is necessary that the liquid is used at a temperaturebelow its boiling point.

At the infeed end of the press, at the right in FIG. 1, where thematerial mat is inserted between the press plates, the plates may becooled when heat setting adhesive is used for the bonding of thematerial. This is designed to prevent the adhesive outside the press,not subjected to pressure, from being prematurely set due to heatradiation from the press plates. The cooling is suit ably carried out byconducting a cooling agent through borings in the infeed end of theplates. According to the embodiment illustrated in the figures, theagent is conveyed to the mobile press by means of flexible tubesattached to pendling toggle joint pipes 8 and 9.

During the forward and backward movements of the press, parts of thematerial mat above the press track are unsupported by the press, and areconsequently liable to excessive deflection. To prevent this, the presstrack is furnished with a number of movable rolls 11, which suit ablydistanced support those parts of the material mat over the track whichare not carried by the press. The rolls ride on rails 12 along the presstrack, and are connected to each other as well as to the press by meansof chains or similar means 13, which enable the rolls to bealternatively moved closer to or further away from each other inaccordance with the movements of the press.

If for some reason the material mat did not properly disengage from thepress plates at the opening of the press, this at the start of thereturn movement cause damage to the unpressed material in front of thepress. This risk is eliminated by the press track having a speciallocking device, which on the one hand prevents the material from movingin reverse, and on the other hand disengages the material from the pressplates at the start of the return movement. This device may consist of apair of friction rolls, situated at the outfeed end of the press trackbetween which the material mat is passed; these rolls have theirrotation barred so that the material 'mat is allowed to move in itsforward direction only. The locking device may also, as shown in thefigure, include pivoted stoppers 15; if the material mat is movedbackwards, these instantly engage as a result of friction and lock thematerial.

FIGURES 3 and 4 show an embodiment of the drive which effects theforward and backward movements of the press. These movements have to becarried out according to an exact scheme, which requires that the returnmovement, notwithstanding the mass of the press, has to be carried outin the shortest possible time, whereas the forward movement has to takeplace at the rate of the travelling material, irrespective of its speedvariations, and additionally in absolute synchronization with it. Thesedemands on the versatility and precision of the movements are met by thedrive described below. Starting with the return movement, this isaccording to the embodiment actuated by electromotor 21, which acts upondrum 26 on shaft 25 over gear 23, 24, and which action is controlled bymeans of magnetic coupling 22. Wire 27, which is wound on drum 26 hasits ends 28 and 29 attached to the press as illustrated in FIG. 1,transfers the power from shaft 25 to the press. The forward movement ofthe press is according to the embodiment actuated by weight 14 (seeFIG. 1) which by means of wire 30 is suspended in mast 7 and revolvesdrum 31 on shaft 25 in a direction opposite to the rotationcorresponding to the return movement of the press. The mass of weight 14is dimensioned so that it can accelerate the press. The twocounteracting power sources, electromotor 21 and weight 14, make themotion cycle of the press proceed as follows. Before the end of thereturn stroke and at a distance equal to the retardation stretch of thepress, determined by its mass, its travelling friction and thecounteraction of weight 14, elec- D tromotor 21 is disengaged and thepress allowed to proceed by its motive energy until the return movementis completed. Nevertheless, owing to weight 14, after the dead point thepress automatically begins moving in the opposite direction, i.e. thatof the forward stroke. The weight causes, the press to accelerate, andat the point where the acceleration reaches the speed of the travellingmaterial mat, its motion is barred by a blocking device, which allowsthe press to move at the speed of the travelling mat only, therebyenabling the press to be closed on the material mat. For the sake ofsimplicity, this blocking device is shown in the figures in the form ofa ratchet wheel with a co-acting pawl. The ratchet wheel, indicated byreference 34, is fixed on shaft 25, and allows this to revolve freelywith respect to the pawl, reference 35, in a direction corresponding tothat of the return stroke of the press. Pawl 35 is mounted on sprocketwheel 32, which by means of chain drive 33 is connected to the drivewhich causes the travel of the material. This travelling and therotation of the pawl are thus operated by the same source of power, i.e.by the drive causing thetravel of the material mat, by reason of whichthe two movements can be made to coincide. Accordingly, during theforward, pressing stroke the press has to travel at a rate which issynchronous with that of the material mat from the moment the ratchetengages the pawl, as the travel of the press, as well as that of thematerial mat, is subsequently controlled only by the drive which causesthe material mat to travel. After the completion of the forward stroke,the press is returned by motor 21 to the starting point of the forwardmovement, and as ratchet wheel 34 is free to move with respect to pawl35, the return can be made at any speed desired. The rotation of shaft25 during the return movement hoists weight 14, and thus there is storednew energy for the succeeding forward movement.

FIG. 5 shows a modification of the driving equipment illustrated in FIG.3; here, wire drum 26 is replaced by a sprocket wheel 126, and wire 27by a chain 127. The ends of the chain 127 are attached to the press inthe same way as the ends of the wire 27.

FIG. 6 shows still another modification, in which the drum and wireshown in FIG. 3 are replaced by gear wheel 226 engaging rack 227attached to the press.

The drive arrangement shown in FIG. 7 differs from that of FIG. 3, asthe electromotor and the weight are replaced by a double actinghydraulic or pneumatic pressure cylinder 36, by which rack 37 is drivenforward and backward. Rack 37 actuates rack 3-8 attached to the press bymeans of spur gearing 39, 46. The blocking device which ensures thesynchronous motion of the press and the material mat during the pressingoperation, and which allows the faster return motion of the press,corresponds substantially to the blocking arrangement indicated byreferences 32, 33, 34 and 35 in FIGS. 3 and 4. In order to avoid animpractically long operation stroke of pressure cylinder 36, gearing 39,40 is dimensioned so that rack 38, i.e. the press, moves the desireddistance, even if the stroke of rack 37 is shorter. This possibility isindicated in the draWing by showing gear wheel 40 considerably largerthan gear wheel 39.

Of course, it is also possible to arrange the forward and backwardmotion of the press by means of hydraulic pistons which act directly onthe press, and with strokes that correspond to the travelling distanceof the press. However, in most cases, this construction is uneconomicaland difiicult to realize, as the travel distance of presses of this typeis seldom below meters, and the construction of pressure cylinders forstrokes of these lengths involves very intricate technical problems.

For big and heavy presses, short pressure cylinders or jacks aresuitable as supplementary sources of power in addition to the drivearrangement shown in FIGS. 3-7. For the acceleration and retardation, ofthe press, especially for the return stroke, considerable expenditure offorce is required because of the substantial mass of the press. Toobviate the necessity of having the ordinary drive dimensioned to dealwith these forces which are needed only momentarily and are many timesgreater than the force required for the uniform travel of the press, itis of advantage to have the acceleration and the retardation effected byspecial pneumatic or hydraulic pressure cylinders, or jacks 41 and 42mounted on the track as shown in FIG. 1. When the press is to beaccelerated at the beginning of its return stroke, a pressure agent isled into cylinder 41 by means of an inlet valve, and thus the piston ofthe cylinder actuates the press and increases its velocity to the ratedesired. At the other end of the press track, where the press has to beretarded, the motive energy of the press can be absorbed by suitablethrottling of the pressure agent in cylinder 42. By connecting thecylinders or jacks 41 and 42 to each other by the way of an accumulator,the kinetic energy absorbed from the press at retardation can be stored:by the accumulator 53, and then used again for the subsequentacceleration of the press. In this way no external power is required inorder to carry out the heavy work entailed by the accelerationandretardation of the press.

FIG. 8 shows schematically a detail of the control arrangement by whichare maneuvered the movements of the press and the press plates. Thecontrol is effected according to the embodiment by means of electricalimpulses emitted by limit switches located along the track. Here, aspecial problem is posed by the impulse for the closing of the press atthe beginning of the forward movement. As the press cannot be closedbefore its travel coincides with that of the material, prior to itsclosing the press has to move a distance which corresponds to theacceleration of the press after its halt at the turning point. As duringits return movement the press is subjected to the influence of varying,external forces, the location of the turning point may differ somewhatfrom one operational cycle to another; as a consequence there is noguarantee that the necessary distance of acceleration is available oneach occasion. In order to eliminate this risk, a special arrangementfor the control system is essential. This arrangement is shown in thefigure, where reference 43 indicates a rail attached to the track at theside of the press. On this rail there rides a cam 44 which is movable onthe rail so that the sliding of the cam requires more force than doesthe actuating of limit switch 47 with which the cam co-operates. Thesliding of the cam is efiectuated by pushers 45 and 46, which, likelimit switch 47, are attached to the mobile press. The arrangementfunctions as follows: the figure illustrates the situation at theturning point of the press, prior to its forward movement, when pusher45 has thrust cam 44 into position A. On the forward movmeent if thepress in the direction of arrow 48, limit switch moves with the pressthe acceleration stretch 49 before it is actuated by cam 44, which emitsthe impulse for the closing of the press. Before the press ends itsforward movement, it moves, by means of pusher 46, cam 44 into positionB, which position enables cam 44 on the subsequent return stroke of thepress to be thrust by pusher 45 to a new position A1 which correspondsto the turning point of this particular stroke, following which thecycle is repeated. When limit switch 47 passes cam 44 at the returnmovement of the press, of course, no impulse is emitted for the closingof the press.

Other methods of applying the principle of the invention may be employedinstead of those explained above. Changes being made in the detailsdescribed, provided the features stated in any of the following claims,or the equivalent of such, be employed.

What is claimed is:

1. A method for the continuous pressing of materials, especially thosein the form of a continuously progressing, unbroken mat, such asdifferent types of wooden and fibrous sheet materials, which comprisesthe steps of: conveying the material to be pressed through the pressplates of a mobile press, accelerating said press in a forwardhorizontal direction which corresponds to the direction of progress ofthe material, synchronizing the speed of the movement of the press withthe speed of movement of the material by blocking said acceleration bymeans of the driving equipment progressing the material, closing thepress to compress the material during the synchronized movement, openingthe press, breaking said blocking, retarding the press, and driving thepress in a backward direction to the starting point of its forwardmovement in order to enable the operation cycle to be repeated on thesucceeding section of the material to be pressed.

2. A method for the continuous pressing of materials, especially thosein the form of a continuously progressing, unbroken mat, such asdifferent types of wooden and fibrous sheet materials, which comprisesthe steps of: conveying the material to be pressed through the pressplates of a mobile press, accelerating and driving said press in aforward horizontal direction which corresponds to the direction ofprogress of the material, closing the press to compress the materialduring the forward movement,

synchronizing the speed of the forward movement of the press duringcompression with the speed of movement of the material, opening saidpress, absorbing kinetic energy from the press during its phase ofretardation in an accumulator for use at the subsequent acceleration.phase, and driving the press in a backward direction at a faster speed,to the starting point of its forward movement in order to enable theoperation cycle to be repeated on the succeeding section of the materialto be pressed.

References Cited UNITED STATES PATENTS 2,051,011 8/1936 Smith 100207LOUIS O. MAASSEL, Primary Examiner.

1. A METHOD FOR THE CONTINUOUS PRESSING OF MATERIALS, ESPECIALLY THOSEIN THE FORM OF A CONTINUOUSLY PROGRESSING, UNBROKEN MAT, SUCH ASDIFFERENT TYPES OF WOODEN AND FIBROUS SHEET MATERIALS, WHICH COMPRISESTHE STEPS OF: CONVEYING THE MATERIAL TO BE PRESSED THROUGH THE PRESSPLATES OF A MOBILE PRESS, ACCELERATING SAID PRESS IN A FORWARDHORIZONTAL DIRECTION WHICH CORRESPONDS TO THE DIRECTION OF PROGRESS OFTHE MATERIAL, SYNCHRONIZING THE SPEED OF THE MOVEMENT OF THE PRESS WITHTHE SPEED OF MOVEMENT OF THE MATERIAL BY BLOCKING SAID ACCELERATION BYMEANS OF THE DRIVING EQUIPMENT PROGRESSING THE MATERIAL, CLOSING THEPRESS TO COMPRESS THE MATERIAL DURING THE SYNCHRONIZED MOVEMENT, OPENINGTHE PRESS, BREAKING SAID BLOCKING, RETARDING THE PRESS, AND DRIVING THEPRESS IN A BACKWARD DIRECTION TO THE STARTING POINT OF ITS FORWARDMOVEMENT IN ORDER TO ENABLE THE OPERATION CYCLE TO BE REPEATED ON THESUCCEEDING SECTION OF THE MATERIAL TO BE PRESSED.